The gorillas, who are 19-year-old half-brothers, are named Ntondo and Mbundi.

Kansas City Zoo spokeswoman Julie Neemeyer said the gorillas escaped Sunday afternoon when a doorway separating their holding area from the keepers' area was apparently left unlatched.

"(Zookeepers) all just started like going up this ladder and they was like jumping out and then they kicked the ladder and then one came sprinting through saying, 'Everyone get out. A gorilla's loose,'" zoo visitor Will Hall said.

The keepers were able to use a ladder over a retaining wall to get to safety

"Security personnel were waving their hands saying, 'There's a gorilla loose. Everybody back the way they came. No kidding,'" said zoo visitor Matt Jacobs.

Neemeyer said that no patrons were in danger, but as a precaution, they were kept out of the exhibit area where the incident happened. KMBC's Peggy Breit reported that there were about 1,800 visitors at the zoo when the animals escaped.

Zookeepers said hoses were used to convince the gorillas to return to their habitat.

Zoo officials said American Zoo and Aquarium Association and United States Department of Agriculture will investigate the incident.

This is the second animal to escape at the zoo within a year. In May, a Red-Capped Mangabey named Floyd, got out after a zookeeper forgot to close a padlock. The animal was out for about 30 minutes.